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Shanxi aged vinegar (SAV) is a famous cereal vinegar in China, which is produced through a solid-state fermentation where diverse microbes spontaneously and complex interactions occur. Here, combined with the metatranscriptomics, the microbial co-occurrence network was constructed, indicating that Lactobacillus, Acetobacter and Pediococcus are the most critical genera to maintain the fermentation stability. Based on an extensive collection of 264 relevant literatures, a transport network containing 2271 reactions between microorganisms and compounds was constructed, showing that glucose (84% of all species), fructose (67%) and maltose (67%) are the most frequently utilized substrates while lactic acid (64%), acetic acid (45%) are the most frequently occurring metabolites. Specifically, the metabolic influence of species pairs was calculated using a mathematical calculation model and the metabolic influence network was constructed. The topology properties analysis found that Lactobacillus was the key role with robust metabolic control of vinegar fermentation ecosystem and acetic acid and lactic acid were the main metabolites with feedback regulation in microbial metabolism of SAV. Furthermore, systematic coordination of positive and negative impacts was proved to be inevitable to form flavor compounds and maintain a natural microbial ecosystem. This study provides a new perspective for understanding microbial interactions in fermented food.

Abstract Particulate organic nitrates (pON) significantly contribute to the mass of organic aerosol and influence the nitrogen oxides cycle in the atmosphere, but their evolution and lifetime remain uncertain. This study performed simultaneous measurements on the anthropogenically affected surface site and the mountain site on top of the polluted planetary boundary layer (PBL). After aging in the PBL, organic nitrate was converted from primary sources (decreased from 8.7% to 4.3%) to secondary sources (increased from 6.3% to 36.1%), spanning from the surface to the mountain. The evaporation of more volatile inorganic nitrate and the production of secondary organic nitrate during aging in the PBL contributed to the enhanced pON fraction over the top of PBL. The contribution of light absorption by brown carbon increased by 57% at the top of PBL compared to the surface, consistent with the higher fraction of nitrogenous organic aerosols over the mountain. The results provide field evidence that the nitrogenous organic aerosols (OA) may be preserved by adding into secondary OA and significantly contribute to the enhanced importance of brown carbon after aging during vertical transport in the PBL.

Abstract Interregional grain trade affects the environment while balancing supply and demand. However, what relationship exist between national carbon emissions reduction and nitrogen losses reduction in each export region is unclear. Here we used maize as a case study to address this gap by combining life cycle assessment method with linear programming model. We found that interprovincial maize trade can reduce the country’s overall carbon emissions and nitrogen losses. However, the carbon and nitrogen reduction potential varied across exporting provinces. Northeast provinces have great potential to reduce the country’s overall carbon emissions and nitrogen losses via interprovincial maize trade. Northwest provinces increase the overall carbon emissions but reduce the overall nitrogen losses when transferring out maize. Optimizing interprovincial maize trade schemes can further enhance the country’s overall carbon and nitrogen reduction potential. The research results provide a theoretical reference for China to develop carbon neutral and nitrogen reduction trade schemes.

Understanding the spatiotemporal dynamics of atmospheric PM2.5 concentration is highly challenging due to its evolution processes have complex and nonlinear patterns. Traditional mode decomposition methods struggle to accurately capture the mode features of PM2.5 concentrations. In this study, we utilized the global linearization capabilities of the Koopman method to analyze the hourly and daily spatiotemporal processes of PM2.5 concentration in the Beijing–Tianjin–Hebei (BTH) region from 2019 to 2021. This approach decomposes the data into the superposition of different spatial modes, revealing their hierarchical spatiotemporal structure and reconstructing the dynamic processes. The results show that PM2.5 concentrations exhibit high-frequency cycles of 12 and 24 h, as well as low-frequency cycles of 124 and 353 days, while also revealing spatiotemporal modes of growth, recession, and oscillation. The superposition of these modes enables the reconstruction of spatiotemporal dynamics with a mean absolute percentage error (MAPE) of only 0.6%. Unlike empirical mode decomposition (EMD), Koopman mode decomposition (KMD) method avoids mode aliasing and provides a clearer identification of global and key modes compared to wavelet analysis. These findings underscore the effectiveness of KMD method in analyzing and reconstructing the spatiotemporal dynamics of PM2.5 concentration, offering new insights into the understanding and reconstruction of other complex spatiotemporal phenomena.

Redistribution of black carbon from the inorganic core to the organic coating of aged aerosols due to liquid-liquid phase separation can reduce radiative absorption by up to 34%, according to field observations and laboratory experiments.

The microphysical attributes of black carbon (BC) can determine its absorption and hygroscopic properties. However, long-term information is difficult to obtain from the field. In this study, the BC properties including mass concentration, the coating volume ratio (VR) relative to the refractory BC (rBC), the rBC diameter and the fraction of cloud condensation nuclei (CCN), are derived from a number of field experiments using a random forest model. This model effectively derives the long-term BC microphysical properties in the Beijing region from 2013 to 2020 using continuous measurements of particulate matter, gas, BC mass concentration and meteorological parameters. The results reveal notably higher BC coatings (mean VR = 7.2) and a greater fraction of CCN-like BC (51%) in the winter compared to other seasons. Following the implementation of national air pollution control measures in 2017, BC mass exhibited a substantial reduction of 60% (29%) in the winter (summer), and VR decreased by 45% (24%). Apart from the influence of meteorological variations, these can be attributed to the declined primary emissions and the gas precursors which are associated with secondary formation of BC coatings. The reduction of both BC mass loading and coatings leads to its solar absorption decreasing by 50%, and the fraction of CCN-like BC (likely in clouds) decreasing by 23%. Environmental regulation will therefore continue to reduce both direct and indirect radiative impacts of BC in this region.

Abstract The result of Aethalometer model to black carbon (BC) source apportionment is highly determined by the absorption Ångström exponent (α) of aerosols from fossil fuel combustion (α ff) and wood burning (α wb). A method using hourly measured potassium to calculate the α ff and α wb values was developed in this study. Results showed that the optimal α ff and α wb were 1.09 and 1.79 for the whole dataset. The optimal α values in the diurnal resolution were also calculated with α ff and α wb varied in 1.02 –1.19 and 1.71–1.90, respectively. Using the dynamic α values, the Pearson correlation coefficient between BC and potassium from wood burning substantially improved compared to the results derived from the fixed α values. The method developed in this study is expected to provide more reasonable BC source identification results, which are helpful for air quality, climate, and human health modeling studies.

Abstract The role of organic aerosols (OA) as ice nucleating particles (INPs) deserves attention because of their high atmospheric abundance. The low concentration of INPs poses challenges in identifying the ice nucleation (IN) of OA among a mix of aerosol types in ambient environment. This study coupled a catalytic stripper system (350°C heating) with a continuous flow diffusion chamber to online investigate the immersion INPs of ambient particles at −30°C at a suburban site. Significant reduction (71 ± 25%) of INP concentrations after evaporation suggested that INPs can be significantly contributed by volatile OA. In addition, nonvolatile OA were more efficient INPs than black carbon. Oxygenated OA by photooxidation and lower ambient promoted the IN activity at noon, when the OA may be more viscous. These results hereby present the first field evidence that OA in anthropogenically influenced regions can be efficient INPs well above the homogeneous IN temperature.

Abstract The less improvement of ambient visibility suspects the government’s efforts on alleviating PM2.5 pollution. The COVID-19 lockdown reduced PM2.5 and increased visibility in Wuhan. Compared to pre-lockdown period, the PM2.5 concentration decreased by 39.0 μg m−3, dominated by NH4NO3 mass reduction (24.8 μg m−3) during lockdown period. The PM2.5 threshold corresponding to visibility of 10 km (PTV10) varied in 54–175 μg m−3 and an hourly PM2.5 of 54 μg m−3 was recommended to prevent haze occurrence. The lockdown measures elevated PTV10 by 9–58 μg m−3 as the decreases in PM2.5 mass scattering efficiency and optical hygroscopicity. The visibility increased by 107%, resulted from NH4NO3 extinction reduction. The NH4NO3 mass reduction weakened its mutual promotion with aerosol water and increased PM2.5 deliquescence humidity. Controlling TNO3 (HNO3 + NO3 −) was more effective to reduce PM2.5 and improve visibility than NH x (NH3 + NH4 +) unless the NH x reduction exceeded 11.7–17.5 μg m−3.

Abstract Background Yellow nutsedge is a unique plant species that can accumulate up to 35% oil of tuber dry weight, perhaps the highest level observed in the tuber tissues of plant kingdom. To gain insight into the molecular mechanism that leads to high oil accumulation in yellow nutsedge, gene expression profiles of oil production pathways involved carbon metabolism, fatty acid synthesis, triacylglycerol synthesis, and triacylglycerol storage during tuber development were compared with purple nutsedge, the closest relative of yellow nutsedge that is poor in oil accumulation. Results Compared with purple nutsedge, high oil accumulation in yellow nutsedge was associated with significant up-regulation of specific key enzymes of plastidial RubisCO bypass as well as malate and pyruvate metabolism, almost all fatty acid synthesis enzymes, and seed-like oil-body proteins. However, overall transcripts for carbon metabolism toward carbon precursor for fatty acid synthesis were comparable and for triacylglycerol synthesis were similar in both species. Two seed-like master transcription factors ABI3 and WRI1 were found to display similar transcript patterns but were expressed at 6.5- and 14.3-fold higher levels in yellow nutsedge than in purple nutsedge, respectively. A weighted gene co-expression network analysis revealed that ABI3 was in strong transcriptional coordination with WRI1 and other key oil-related genes. Conclusions These results implied that pyruvate availability and fatty acid synthesis in plastid, along with triacylglycerol storage in oil bodies, rather than triacylglycerol synthesis in endoplasmic reticulum, are the major factors responsible for high oil production in tuber of yellow nutsedge, and ABI3 most likely plays a critical role in regulating oil accumulation. This study is of significance with regard to understanding the molecular mechanism controlling carbon partitioning toward oil production in oil-rich tuber and provides a valuable reference for enhancing oil accumulation in non-seed tissues of crops through genetic breeding or metabolic engineering.

Introduction Ovarian cancer (OC) is the malignant tumor with the highest mortality among gynecological cancers. Chemotherapy resistance is a major obstacle to OC therapy. Circular RNAs (circRNAs) play crucial roles in cancer development and chemoresistance. However, the role and potential mechanism of has-circ-001567 (circ-VPS13C) in chemoresistance of OC remain unknown. Material and methods The levels of circ-VPS13C, miR-106b-5p and 14-3-3 zeta (YWHAZ) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell Counting Kit-8 (CCK-8) assay was used to assess cell viability and calculate the half inhibition concentration (IC 50 ) of cisplatin (DDP). The levels of autophagy-related markers were measured by western blot assay. Cell apoptosis and migration were evaluated by flow cytometry and transwell assay, respectively. The binding relationship between miR-106b-5p and circ-VPS13C or YWHAZ was confirmed by dual-luciferase reporter assay. Xenograft assay was performed to explore the role of circ-VPS13C in vivo. Results Circ-VPS13C and YWHAZ were up-regulated, while miR-106b-5p was down-regulated in DDP-resistant OC tissues and cells. Knockdown of circ-VPS13C enhanced DDP sensitivity by repressing autophagy in DDP-resistant cells. Circ-VPS13C increased DDP resistance via sponging miR-106b-5p. Moreover, miR-106b-5p directly targeted YWHAZ. Up-regulation of YWHAZ alleviated the decrease in DDP resistance caused by circ-VPS13C depletion. In addition, circ-VPS13C silencing decreased DDP resistance in vivo. Conclusions Circ-VPS13C knockdown enhanced DDP sensitivity of OC through modulation of autophagy via the miR-106b-5p/YWHAZ axis, providing a new biomarker for improving the efficacy of OC chemotherapy.

How sulfur dioxide emitted through coal combustion is oxidized to sulfate particles during winter haze pollution events has been the subject of debate. Here, the authors show that rapid oxidation takes place by nitrogen dioxide and nitrous acid, producing nitrous oxide together with sulfate.

Residential coal combustion (RCC) emission exhibited obvious daily variation, while no real-time estimation of air pollutants from RCC has been reported, as the shortages of corresponding activity dataset and emission factors with high time resolution. A real-time monitoring platform for RCC emission was established. Hourly emission factors of 18 typed of TEs from eleven kinds of chunk coals and nine kinds of honeycomb coals burning in China were obtained. The monthly and hourly coal consumption amounts were calculated with reference and our field survey. Then the hourly TEs emission inventories from RCC were established in China. GEOS-Chem and Risk Quotients Models were utilized to map the spatialized health risks of hazardous elements, including the gridded hazard index and carcinogenic risk. The result indicated that the EFs of TEs would be underestimated if the tests only consider flaming conditions. Cu, K, Ca, Zn, and Co were the top five elements from RCC, with corresponding emission amounts as 1397.7, 1054.0, 676.0, 623.5 and 420 tons in 2017, respectively. K, Ti, Fe, Sn, and Sb showed hourly peak values under flaming dominated periods, accounting for 48.2%, 45.9%, 31.8%, 42.8%, and 33.8% of their daily emissions. Other elements (e.g., V, Co, As, Hg and Pb) exhibited higher emissions under smoldering dominated period in nighttime, accounting for 22.2%, 32.9%, 27.6%, 34.7%, and 28.4% of their daily emissions. TEs emission from RCC closely follows the habits of human daily cooking and heating activity. The national HI were lower than the acceptable level (HI ≤ 1) except Sichuan Province (up to 1.2). Higher carcinogenic risks (≥1 × 10-6) occurred in parts of Sichuan, Shanxi, Hunan and Hubei, which were up to 2.0 × 10-5. The high-resolution TEs emission inventories could be useful for future modeling works on the formation and evolution of air pollution and are helpful for human exposure assessment.

Biomass burning (BB) has significant impacts on air quality, climate and human health. In China, the BB emission has changed substantially over the past decades while the multi-year variation held high uncertainty and the driving forces have addressed little attention. Here, this research aimed to conduct a comprehensive and systematic analysis of BB variation in China and provided precise and targeted BB emission reduction suggestions. The moving of high emission for BB from 2003 to 2014 was clearly identified, by the view of reliable emission estimation and anthropogenic impacts. Multiple satellite products, field survey, time varying biomass loading data and measured emission factors were adopted to better estimating BB emission and reducing the uncertainty. Social-economic analysis was added to assess the anthropogenic impacts on high emission variation quantitatively. Results showed that the cumulative BB emissions of OC, EC, CH4, NOX, NMVOC, SO2, NH3, CO, CO2, PM2.5 and PM10 during 2003-2014 were 1.6 × 104, 5.64 × 103, 3.57 × 104, 1.7 × 104, 5.44 × 104, 2.96 × 103, 6.77 × 103, 6.5 × 105, 1.15 × 107, 5.26 × 104 and 6.04 × 104 Gg, respectively. Crop straw burning (in-field and domestic) in northeast China plain (NEP), north China plain (NCP), northern arid and semiarid region and loess plateau were the key sources, averagely contributed 73% for all the pollutants emission. While domestic straw burning and firewood burning in Sichuan basin (SB), Yunnan-Guizhou plateau and southern China were main contributors, averagely accounting for 70% of all the pollutants emission. On regional level, high emissions were mainly found in SB, NCP and NEP. Temporally, high emissions were mainly found in crop sowing harvesting and heating seasons. From 2003 to 2014, the BB emission for different biomass species has changed significantly in different regions. High emission has gradually moved from SB to NCP and NEP. Firewood burning and domestic straw burning emission decreased by 47% and 14% in SB, respectively. In-field straw burning emission increased by 52% and 231% in NCP and NEP respectively and domestic straw burning emission increased by 62% in NEP. Emissions from heating season have decreased while emissions in corn harvest season were continuously increased. Analysis of Environmental kuznets curve, agricultural productivity level, human burning habits, rural energy structure and local control policies revealed the internal human driving strength of the variation for BB emission. The unbalanced development of social economy and the policy bias were primary drivers of limiting the BB management. BB emission will alleviate in NCP and aggravate in NEP. For the further emission reduction, effective measures for corn sources management, straw returning and rural energy utilization should be systematically considered. This research provides a clear evidence for the multi-year variation pattern of BB emissions, which is critical for pollution prediction, air quality modeling and targeted mitigation strategies for the key regions of China.

Abstract Atmospheric aerosols in clean remote oceanic regions contribute significantly to the global albedo through the formation of haze and cloud layers; however, the relative importance of ‘primary’ wind-produced sea-spray over secondary (gas-to-particle conversion) sulphate in forming marine clouds remains unclear. Here we report on marine aerosols (PM1) over the Southern Ocean around Antarctica, in terms of their physical, chemical, and cloud droplet activation properties. Two predominant pristine air masses and aerosol populations were encountered: modified continental Antarctic (cAA) comprising predominantly sulphate with minimal sea-salt contribution and maritime Polar (mP) comprising sulphate plus sea-salt. We estimate that in cAA air, 75% of the CCN are activated into cloud droplets while in mP air, 37% are activated into droplets, for corresponding peak supersaturation ranges of 0.37–0.45% and 0.19–0.31%, respectively. When realistic marine boundary layer cloud supersaturations are considered (e.g. ~0.2–0.3%), sea-salt CCN contributed 2–13% of the activated nuclei in the cAA air and 8–51% for the marine air for surface-level wind speed

Abstract Background Cyperus esculentus is unique in that it can accumulate significant amounts of oil, starch and sugar as major storage reserves in tubers with high tuber yield and therefore considered as a novel model to study carbon allocation into different storage reserves in underground sink tissues such as tubers and roots. Sucrose (Suc) plays a central role in control of carbon flux toward biosynthesis of different storage reserves; however, it remains unclear for the molecular mechanism underlying Suc metabolism in underground oil-rich storage tissues. In the present study, a comprehensive transcriptome analysis of C. esculentus oil tuber compared to other plant oil- or carbohydrate-rich storage tissues was made for the expression patterns of genes related to the Suc metabolism. Results The results revealed some species-specific features of gene transcripts in oil tuber of C. esculentus, indicating that: (i) the expressions of genes responsible for Suc metabolism are developmentally regulated and displayed a pattern dissimilar to other plant storage tissues; (ii) both of Suc breakdown and biosynthesis processes might be the major pathways associated with Suc metabolism; (iii) it was probably that Suc degradation could be primarily through the action of Suc synthase (SUS) other than invertase (INV) during tuber development. The orthologs of SUS1, SUS3 and SUS4 are the main SUS isoforms catalyzing Suc breakdown while the vacuolar INV (VIN) is the leading determinant controlling sugar composition; (iv) cytosolic hexose phosphorylation possibly relies more on fructose as substrate and uridine diphosphate glucose pyrophosphorylase (UGP) plays an important role in this pathway; (v) it is Suc-phosphate synthase (SPS) B- and C-family members rather than SPS A that are the principal contributors to SPS enzymes and play crucial roles in Suc biosynthesis pathway. Conclusions We have successfully identified the Suc metabolic pathways in C. esculentus tubers, highlighting several conserved and distinct expressions that might contribute to sugar accumulation in this unique underground storage tissue. The specific and differential expression genes revealed in this study might indicate the special molecular mechanism and transcriptional regulation of Suc metabolism occurred in oil tubers of C. esculentus.

A single particle soot photometer (SP2) was deployed in urban Nanjing, located in the Yangtze River Delta (China), to investigate the mixing state and sources of ambient refractory black carbon (rBC) from 26 January to 25 February 2014, along with an in-situ measurement of submicron aerosol chemical species by an aerodyne aerosol chemical speciation monitor (ACSM). The results showed that anthropogenic activities associated with firework emissions can be a significant source for rBC-containing particles during the period of the Chinese New Year, resulting from the evident peaks of rBC at midnight. During the residual periods, namely regular day (RD), the diurnal cycles of rBC presented two typical peaks that can be attributed to a synergistic influence of local traffic emissions and boundary layer changes throughout a day. Three coating factors, including organics, sulfate, and nitrate (-rich), were resolved using a positive matrix factorization (PMF) approach to explain the potential contribution of non-rBC coatings (i.e., organics, sulfate, and nitrate) to the coating thickness of rBC-containing particles. As the results show, organic aerosols (OAs) might be a major contributor to the coating thickness of rBC-coating particles during the whole period. The relative coating thickness (a ratio between coated particle size to BC core) exhibited a positive relationship with sulfate, indicative of the favorable coating factor during the episode caused by firework emissions. Source apportionment of rBC was performed via a multiple linear regression between the total rBC mass and each ACSM-PMF factor (rBC-ACSM-PMF). On average, biomass burning emissions accounted for 43%, being the largest contributor during the RD period, whereas local traffic emissions played a major role during the new year time.

The fast development of a secondary aerosol layer was observed over megacities in eastern Asia during summertime. Within three hours, from midday to early afternoon, the contribution of secondary aerosols above the planetary boundary layer (PBL) increased by a factor of three to five, and the coatings on black carbon (BC) also increased and enhanced its absorption efficiency by 50%. This tended to result from the intensive actinic flux received above the PBL which promoted photochemical reactions. The absorption of BC could be further amplified by the strong reflection of solar radiation over the cloud top across the PBL. This enhanced heating effect of BC introduced by combined processes (intensive solar radiation, secondary formation and cloud reflection) may considerably increase the temperature inversion above the PBL. This mechanism should be considered when evaluating the radiative impact of BC, especially for polluted regions receiving strong solar radiation.

Introduction: Ovarian cancer (OC) is the malignant tumor with the highest mortality among gynecological cancers. Chemotherapy resistance is a major obstacle to OC therapy. Circular RNAs (circRNAs) play crucial roles in cancer development and chemoresistance. However, the role and potential mechanism of has-circ-001567 (circ-VPS13C) in chemoresistance of OC remain unknown. Material and methods: The levels of circ-VPS13C, miR-106b-5p and 14-3-3 zeta (YWHAZ) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell Counting Kit-8 (CCK-8) assay was used to assess cell viability and calculate the half inhibition concentration (IC50) of cisplatin (DDP). The levels of autophagy-related markers were measured by western blot assay. Cell apoptosis and migration were evaluated by flow cytometry and transwell assay, respectively. The binding relationship between miR-106b-5p and circ-VPS13C or YWHAZ was confirmed by dual-luciferase reporter assay. Xenograft assay was performed to explore the role of circ-VPS13C in vivo. Results: Circ-VPS13C and YWHAZ were up-regulated, while miR-106b-5p was down-regulated in DDP-resistant OC tissues and cells. Knockdown of circ-VPS13C enhanced DDP sensitivity by repressing autophagy in DDP-resistant cells. Circ-VPS13C increased DDP resistance via sponging miR-106b-5p. Moreover, miR-106b-5p directly targeted YWHAZ. Up-regulation of YWHAZ alleviated the decrease in DDP resistance caused by circ-VPS13C depletion. In addition, circ-VPS13C silencing decreased DDP resistance in vivo. Conclusions: Circ-VPS13C knockdown enhanced DDP sensitivity of OC through modulation of autophagy via the miR-106b-5p/YWHAZ axis, providing a new biomarker for improving the efficacy of OC chemotherapy. [ABSTRACT FROM AUTHOR]

The microphysical properties associated with the ice production importantly determine the precipitation rate of clouds. In this study, the microphysical properties including the size distribution and particle morphology of water and ice for stratocumulus during an extratropical cyclone over the northern China were in-situ characterized. Stages of cloud were investigated including young cells rich of liquid water, developing and mature stages with high number concentration of ice particles (Nice). The Nice could reach 300 L-1 at the mature stage, about two orders of magnitudes higher than the primary ice number concentration calculated from ice nucleation. This high Nice occurred at about -5 to -12 ⁰C, spanning the temperature region of Hallett-Mossop process and possible other mechanisms for the secondary ice production (SIP). The Nice was positively associated with the number concentrations of large graupel with diameter (d) > 250 μm and large supercooled droplet (d > 50 μm). The SIP rate was 0.005-1.8 L-1s-1 derived from the measured Nice with known ice growth rate between two sizes. The SIP rate could be produced by a simplified collision-coalescence model within an uncertainty factor of 5, by considering the collection of large droplets by graupel. The collection efficiency between was found to increase when the size of droplet was closer to graupel which may improve the agreement between measurement and model. Importantly, the overall Nice was found to be highly related to the distance to cloud-top (DCT). The level with larger DCT had more abundant rimmed graupels falling from the above level, which promoted the coalescence processes between graupels and droplets, producing a higher fraction of smaller ice through SIP. This seeder-feeder process extended the avalanche SIP at lower temperature up to -14 ⁰C beyond the temperature region of Hallett-Mossop process. The results illustrated the microphysical properties of clouds with convective cells under different stages, which will improve the understanding of the key processes in controlling the cloud glaciation and precipitation process. [ABSTRACT FROM AUTHOR]

The cloud condensation nuclei (CCN) activity of black carbon particles (BC) importantly determines their impacts on cloud microphysics and atmospheric lifetime. This process is crucially determined by the amount of more hygroscopic coating materials BC can acquire during aging process. It remains a challenge for ambient measurements to capture this process and link this with CCN activity of BC. Here by using coupled measurements of size-resolved number concentrations of CCN at configured water supersaturation (SS) and BC24 containing particles (BCc), we are able to directly monitor the droplet activation diameter (D50) and activation fraction of BCc (Fact, BC) in ambient environment. The number concentration of BCc was found to peak at diameter 180-210 nm after acquiring coatings, larger than that for all particles (50-150 nm). This led to that the initially smaller BC can be enlarged and become larger and more hygroscopic, even having higher CCN activities than other particles. The Fact, BC increased from 42% to 69% in number and from 67% to 85% in mass, as SS increased from 0.1% to 0.2%, but tended to reach a plateau when SS>0.2%.Notably, Fact, BC and D50 linearly correlated with equivalent photochemical age, at a rate of +2% per hour and -3nm per hour, respectively. The results suggest BCc from anthropogenic sources can readily serve as CCN at a relatively low SS, and over half of the BC population can be activated in a few hours. This means the surface-sourced BC can efficiently incorporate into clouds and may exert important indirect radiative impacts. [ABSTRACT FROM AUTHOR]